Important Requirements for Concrete Inspection and Acceptant

Inspecting the concrete quality inclusive the inspection of materials, equipments, production process and the characteristics of the already solidifying concrete The slump of the concrete mixture is inspected at the Site in accordance with the following regulations:

• For the concrete mixed at Site, need to inspect immediately after mixing the initial batch

• For the pre-cast concrete at the concrete mixing station (commodity concrete), need to inspect for each delivery at the concrete placing site

• When mixing concrete under the stable weather condition and material moisture, inspect once per shift

• When there is change in type and moisture of the material as well as change the compositions for providing & mixing concrete, need to inspect at once the initial mixing batch, then, further inspecting at least once per shift.

The testing samples for determining the concrete strength need to be taken according to each group. Each group will include three units of sample taken at the same time at one position in accordance with the regulations. The quantity of sample group will be regulated according to the weight as follows:

For the great concrete block, take one sample group per 500 m3 when the weight  in one placing block greater than 1000 m3 and take one sample group per 250 m3 when the concrete weight in one placing block less than 1000 m3.

• For the big foundation, take one sample group per 100 m3 but not less than one sample group per one foundation block

• For the concrete of machinery foundation, take one sample group for the placing block greater than 50 m3 but still take one sample group for the block less than 50m3

• For the frame and structures of foundation (column, girder, plate, arch …), take one sample group per 20 m3 of concrete 

• In case of placing concrete for single structures with less weight, still take one sample group if necessary;

• For the concrete of floor, road surface (car road, runway, …, take one sample group per 200 m3 of concrete but if the concrete block is less than 200 m3, still take one sample group.

• In order to check the water proof of concrete, take one sample group per 500 m3. but if the concrete block weight is less than this, still take one sample group

The strength of concrete during construction after inspected at the age of 28 days by pressing the casting sample at the Site is considered to meet the designing requirements when the average value of each sample group is not less than designing grade and no sample in the sample group getting the strength below 85% of designing grade